The present invention relates to a lamp ballast, in particular, to a lamp ballast for powering instant start fluorescent lamps. Further, the present invention allows a plurality of such instant start lamps to be driven by the ballast circuit of which the ballast control IC of the present invention is a part.
There is a need for simplified ballast control integrated circuits for controlling electronic ballasts. Electronic ballasts provide significant advantages over electromagnetic ballasts including greater efficiency and greater ability to control the lamps. There are a number of such electronic ballast control IC's on the market including the IR2157 and 2167 family of ballast control IC's. The 2157 family is a 16-pin device and the 2167 family is a 20-pin device. These devices include many functions and it is often desirable to provide a control integrated circuit which has fewer pins to thereby simplify circuitry and reduce costs. An example of such a ballast control integrated circuit is the IR2520D integrated circuit which is an adaptive ballast control integrated circuit having only eight pins.
There is a need for a ballast control integrated circuit for controlling multiple instant start fluorescent lamps and having a reduced number of pins and which thus allows a reduction in the complexity of the external circuitry and components connected to the control IC.
There is furthermore a need for an instant start fluorescent lamp ballast control integrated circuit.
There is furthermore a need for an instant start ballast control circuit which allows the control of a plurality of instant start lamps wherein the brightness level of the lamps is maintained constant regardless of the number (up to a maximum number) of lamps connected to the ballast control circuit and which maintains a constant brightness level when lamps are removed.
There is furthermore a need for a ballast control circuit that insures that all of the multiple lamps are ignited.
Furthermore, there is a need for such a ballast control circuit which prevents hard switching, and thus attendant damage to the ballast switches, in the event of lamp removal.